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Biomedical subjects

N Okuda

Publications and source records attributed to N Okuda.

At least 55 records · Page 3Linked to original sources
PubMed1986

[Non-invasive estimation of aortic flow by local electrical impedance changes].

Aortic flow velocity was measured by catheter-tip flow transducer in 25 patients who underwent left cardiac catheterization for non-invasive estimates by the impedance method. Disk electrodes were attached to the skin at the levels of the second thoracic vertebra in the posterior median line and the V8 lead position for electrocardiography. Alternating current, 350 micro-amperes, 50 KHz constant, was applied to the outer electrode, and impedance changes were detected via the inner electrode. The e wave, or height of the first derivative dz/dt wave of the electrical impedance was lower in cases of old myocardial infarction and higher in cases of aortic valve regurgitation, as compared with the values of the healthy control group. The time lag between the start of the upward deflection and the peak value of the dz/dt wave coincided with that of the aortic flow curve as measured at the aortic arch and descending aorta. These time lags were about 20 to 30 msec as compared with the ascending aortic flow curve, and were -20 to -30 msec as compared with the abdominal aortic flow curve. There was a close correlation between the maximum flow velocity measured at the aortic arch and the height of the e waves. The regression equation was: Y = 0.21X - 1.53, r = 0.88, p less than 0.01. These data suggest that the first derivative of electrical impedance change as obtained by the disk electrode method reflects aortic flow at the arch and descending aorta.

Adult↗
PubMed1980

Effects of heat acclimation of distance runners in a moderately hot environment.

Five distance runners (H groups) performed a 60 min bicycle exercise at a load of 60--70% VO2max in a moderately hot environment (Ta: 33.5 degree C, 60% RH). Following a period of heat acclimation with bench-stepping at a load equal to about 25--30% VO2max, in a hot environment (Ta: 45--50 degree C, 30--40% RH) for 9 days, the work test was repeated. Two control subjects (R) performed the same work tests with no heat acclimation. Heat acclimation increased performance time. Rectal temperature, mean skin temperature, heart rate, and Na+ concentrations in sweat were lower in H and, with one exception, sweat rate was higher after heat acclimation. All H subjects demonstrated that the linear relationship between sweat rate and rectal temperature was shifted to a lower temperature (threshold shift). This shift correlated with a lowering of resting rectal temperature. The magnitude of the reduction in those two temperatures due to heat acclimation was identical. The observed improvement of work performance in moderate heat following heat acclimation to a higher temperature is attributed to a more efficient thermoregulatory mechanism.

Acclimatization↗
PubMed1980

Periodic ACTH discharge.

A 9 1/2-year-old girl is presented who had cyclical attacks of abdominal pain, vomiting, emotional disturbance, and marked weight change for two years. Associated findings were facial plethora, hypertension, transient hyperglycemia and glycosuria, elevated plasma ACTH, cortisol, and urinary 17-OHCS excretion, and low plasma osmolality with hyponatremia. Urinary excretion of catecholamines and porphyrin metabolites was not increased. Between episodes, she showed no abnormal clinical signs or laboratory data. The attacks were effectively suppressed with the administration of chlorpromazine. The disorder appears to be due to the periodic release of excessive ACTH; the cause remains unknown.

Adrenocortical Hyperfunction↗
PubMed1980

Suppression of pokeweed mitogen-induced differentiation of human B cells by in vitro levamisole-treated T lymphocytes.

The generation of immunoglobulin-producing cells from human peripheral blood lymphocytes in pokeweed mitogen-simulated cultures was significantly suppressed by levamisole. Greatest suppression was observed when cells were incubated with levamisole at a concentration of 10(-6) M for 20 min or more prior to culture. Such suppression occurred when untreated as well as levamisole-treated B cells were co-cultured only with levamisole-treated T cells. Adding of levamisole-treated T cells to a combination of untreated autologous B and T cells resulted in the suppression of B cell differentiation. The results suggest that levamisole treatment of lymphocytes exerts suppression on pokeweed mitogen-induced B cell differentiation through its effect on T cell regulatory properties.

Adult↗
PubMed1980

Effects of endurance training on thermoregulation in females.

Thermoregulatory responses to heat have been evaluated at rest in 27 university students; 11 female competitive athletes, 8 male non-athletes, and 8 female non-athletes. They rested for 2 h in an ambient temperature of 32 degrees C, 40% RH with their legs immersed up to the knees in a stirred water bath of 42 degrees C. Sweat rates of the female athletes were higher than the female non-athletes, but lower than the male non-athletes. Core temperature threshold for sweating was significantly lower in the female athletes than in the male and female non-athletes. The slope in sweat rate/core temperature relationship of the female athletes was nearly parallel to that of the female non-athletes. The thermoregulatory responses observed in the female athletes are thought to be comparable to those produced by heat adaptation. Comparing the heat responses in male and female non-athletes, no distinct sexual differences were observed in the rise in core temperature, mean skin temperature, and the core temperature threshold for sweating. On the other hand, the slope in the sweat rate/core temperature relationship was significantly steeper in males than in females. The beneficial modifications of heat responses demonstrated in the present study in female athletes are similiar to those observed in male athletes.

Adult↗
PubMed1979

Induction of suppressor activity on B-cell differentiation in human T-cell subset without fc(IgG) receptors by levamisole administration.

A single oral dose of 150 mg levamisole was administered to five healthy adults. Circulating Fc(IgG) receptor-bearing T cells (T gamma cells) increased for 5 days after levamisole intake, but total E rosette-forming cells showed no significant alterations. The generation of immunoglobulin-producing cells in the peripheral blood lymphocytes (PBL), which was induced in the in vitro pokeweed mitogen (PWM)-stimulated cultures, was significantly suppressed for 5 days after levamisole administration. Suppressor T-cell activity on B-cell differentiation, which was induced by levamisole intake, was evaluated by co-culturing with allogeneic untreated adult PBL in the PWM system in six other volunteers. A seemingly dose-dependent suppression on B-cell differentiation was exerted by T cells isolated on day 3 of levamisole treatment, but not by T cells differentiation was exerted by T cells isolated on day 3 of levamisole treatment, but not by T cells which were isolated before or on day 14 of the experiment. When T cells were fractionated into two subsets with regard to the presence or absence of Fc(IgG) receptors, suppressor T-cell activity appeared to be generated by levamisole largely in T cells lacking Fc(IgG) receptors, but not in T gamma cells.

Adult↗
PubMed1979

Suppression of adult B cell differentiation in pokeweed mitogen-stimulated cultures by Fc(IgG) receptor-negative T cells from cord blood.

Unfractionated T lymphocytes from cord blood suppressed adult B cell differentiation into immunoglobulin-producing cells in pokeweed mitogen-stimulated co-culture system. Cord blood T cells were fractionated into T cells bearing Fc receptors for IgG (Tgamma cells) and T cells lacking Fc receptors for IgG(Tnon-gamma cells) by rosette formation with ox erythrocytes coated by the IgG fraction of rabbit antisera followed by Ficoll-Hypaque gradient sedimentation. T gamma cells from cord blood, even though isolated after the interaction with immune complexes, showed no suppressor activity on adult B cell differentiation, whereas Tnon-gamma cells exerted strong suppression to a similar extent to that by unfractionated cord T cells. The suppressor activity on B cell differentiation by Tnon-gamma cell as well as by unfractioned T cells from cord blood was completely abrogated by irradiation with 2000 rads. These results indicated that, contrary to suppressor function found in adult T cells, the suppressor activity in cord T cells might be exerted by a T cell subset lacking Fc receptors for IgG(Tnon-gamma cells).

Adult↗
PubMed1978

Transient increase of IgG Fc receptor-bearing T lymphocytes following positive PPD skin testing.

In tuberculin-sensitive individuals, IgG Fc receptor (FcR)-bearing lymphocytes in the peripheral blood increased transiently following PPD-tuberculin skin test. This rise in circulating FcR-bearing cells appeared to peak about 36--48 h after the intradermal inoculation of PPD and seemed to occur largely in the T cell population. Skin test-negative individuals showed no significant changes in their circulating FcR-bearing cells following PPD inoculation. Peripheral blood lymphocytes from PPD-sensitive individuals were fractionated into non-T cell and T cell-enriched populations by E rosette sedimentation technique. FcR-bearing cells in the T cell-enriched population were eliminated by EA rosette sedimentation: i.e. FcR-negative T cells. Then, equal numbers (1 X 10(5) cells each) of non-T cells and unfractionated or FcR-negative T cells were recombined in culture. Prior to PPD inoculation, there was no significant difference between these two cell mixtures in the in vitro cellular response to PPD or mitogens. When these cell populations were obtained 36--48 h after PPD inoculation, however, the combination of non-T cells and FcR-negative T cells responded to PPD much better than the combination of non-T cells and unfractionated T cells, whereas the mitogen-induced cellular proliferation of these two cell mixtures did not differ from each other.

Adult↗